This invention relates to atomizing pump dispensers in general and more particularly to an improved inlet seal for a pump dispenser which seals the inlet chamber during dispensing with a surface to surface seal.
Various types of atomizing pump dispensers have been developed. The majority of these pump dispensers include a pump body in which there is formed a pump chamber, a piston disposed for reciprocal movement within the pump chamber a dispensing stem operatively coupled to the piston and adapted to receive an atomizer head, and valve means for selectively bringing the pump chamber in and out of communication with the container on which the pump is mounted. Typically, a check valve such as a ball check valve is utilized. During the dispensing stroke the pressure developed within the pump chamber closes the check valve so that material is forced out through the stem and atomizer. After dispensing, as the piston is returned to its normal position by biasing means such as a spring, the check valve opens to permit the pump chamber to refill. However, pumps have also been developed which do not utilize such a check valve. Typical of this type of pump is that disclosed and claimed in applicant's U.S. Pat. No. 4,113,145, the disclosure of which is hereby incorporated by reference. In the pump disclosed therein, a throat is formed at the bottom of the pump chamber. Upon actuation of the dispensing stem a cylindrical member makes a positive surface to surface seal with the throat to seal off the chamber from a dip tube in communication with the container. On the return stroke of the piston, the cylinder remains empty until the member making the seal reaches almost its fully raised position whereupon communication is again established between the pump chamber and the container permitting the chamber to refill.
The same manner of sealing the pump chamber is described in U.S. patent application Ser. No. 765,701 in conjunction with a prepressurized pump. In the pump of the aforementioned U.S. Pat. No. 4,113,145, and in a number of the embodiments of Ser. No. 765,701, the throat at the inlet to the pump chamber is formed by molding the throat as part of the pump body. However, in FIG. 4 of U.S. Pat. No. 4,274,560, an alternative manner of sealing is disclosed. This alternative manner comprises forming the throat by means of a flexible insertable seal. This permits making the seal member, which is inserted into the pump chamber, of a softer plastic material than the pump body itself and softer than the cylindrical member with which it makes a seal so as to obtain a better sealing effect.
Another pump of this general type is disclosed in British Pat. No. 1,486,236, in which a check valve is formed at the inlet to the pump chamber by an elastic ring closely and slidably fitted on a valve rod movable between two positions as defined by a cavity member having an annular recess larger than the outside diameter of the elastic ring.